Photographic developer

ABSTRACT

A photographic developer for achieving maximum film sensitivity by increasing the dynamic range of a photographic film which includes an additive mixture of N-(p-hydroxyphenyl glycin) and 1phenyl-3-pyrazolidone.

United States Patent [1 1 Braunstein Dec. 11, 1973 PHOTOGRAPHICDEVELOPER [75] Inventor: Simeon Braunstein, Maiden, Mass.

[73] Assignee: The United States of America as represented by theSecretary of the United States Air Force, Washington, DC.

[22] Filed: Oct. 14, 1971 [21] Appl. No.: 189,327

[52] US. Cl. 96/66 HD, 96/66 R, 96/66.3 [51] Int. Cl G03c 5/30 [58]Field of Search 96/66 HD [56] References Cited FOREIGN PATENTS ORAPPLICATIONS 761,301 ll/1956 Great Britain 96/66 HD PrimaryExaminerNorman G. Torchin Assistant ExaminerM. F. Kelley Attorney-HarryA. Herbert et al.

[57] ABSTRACT 1 Claim, N0 Drawings PHOTOGRAPHIC DEVELOPER BACKGROUND OFTHE INVENTION This invention relates to photography and, moreparticularly, to a novel photographic developing agent.

The problem of obtaining maximum film sensitivity has been of greatconcern to the photographic industry. Numerous approaches have beenexplored in attempting to solve this problem. For example, one methodfor obtaining high sensitivity involves forced development. In otherwords, a prolonged development to the point where the resulting high foglevel becomes unacceptable. Generally, forced development results notonly in maximum sensitivity for the film-developer combinationconcerned, but also maximum gamma. Because of the high film densitiesafter produced, data reduction is difficult and in regions of high andoverexposure, resolution is reduced. Therefore, a developer whichcombines extended dynamic range (low gamma), good resolution at high andover-exposed lev els with high film sensitivity could be relied upon toovercome the problems encountered with forced development.

A phenidone-sodium sulfite developer with great dynamic range and noloss of film sensitivity for the films tested was formulated. However,the gammas obtained (0.12-0.25) for normal contrastfilms were low formany purposes, and in the case of Kodak Royal-X Pan Sheet film, adensity range of only 0.2 was obtained with 10 minutes development at68F. Therefore, this prior art developer did not completely overcome theproblems of prolonged development.

With the present invention, however, the disadvantages resulting fromthe use of forced development or the previously known phenidone-sodiumsulfite developers have been overcome by using an additive mixture ofglycin and phenidone as a developing agent.

The developer of this invention increases the dynamic range of mostfilms. It produces gammas in the 0.3-0.5 range for normal contrast filmsat practicable developing times. There is no significant loss, and inmost cases, appreciable gain in film toe speed as compared with standardprocessing. Resolution in the high and over-exposed regions is improved.The developer can be used successfully in machine processing such as inthe Filmline 5-90 Spray processor.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas been found that maximum film sensitivity for photodeveloped filmscan be achieved by utilizing a glycinphenidone developing agent. Thedeveloper of this invention comprises an aqueous solution of an additivemixture of glycin and phenidone as well as sodium sulfite, sodiumbisulfite and Kodalk. The developer of this invention makes possible lowgamma photography with no less of toe speed during machine processing.It results in increased information in that more information can beprinted on a single print because of the excellent shadow detail and thefully detailed highlights that are achieved.

Accordingly, the primary object of this invention is to provide animproved photographic developer.

Another object of this invention is to provide a photographic developingagent capable of achieving maximum film sensitivity.

Still another object of this invention is to provide a photographicdeveloper that can increase the dynamic range of photographic filmswhile still maintaining good resolution at high and overexposed levelsas well as high film sensitivity.

The above and still other objects and advantages of the presentinvention will become apparent upon consideration of the followingdetailed description of specific embodiments thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The photographic developer ofthis invention comprises an additive mixture of phenidone and glycin incombination with sodium sulfite and sodium bisulfite. It increases thedynamic range of most films and produces gammas in the 0.3-0.5 range fornormal contrast films and about 0.7 for high speed infrared film atpracticable developing times. Glycin is a slow, powerful, fog-freedeveloping agent, extremely resistant to aerial oxidation. It is moreparticularly defined as N-(phydroxyphenyl glycin). Phenidone is moreparticularly defined as l-phenyl-3-pyrazolidone and has the advantage ofa very short induction period. The two developing agents, when combinedin the manner described, form a super additive mixture that isresponsible for achieving the low gammas of this invention.

To further illustrate the invention, there are presented the followingexamples. Example 1 represents the conventional phenidone-sodium sulfitedeveloper heretofore employed in attempting to overcome the problemencountered during forced development. Examples 2 and 3 illustrate thepresent invention.

EXAMPLE I Phenidone l.5 g Sodium Sulfite 30.0 g Water to 1 liter Thedeveloper of Example 1 obtained gammas of 0.12-0.25 for normal contrastfilms and are somewhat low for many purposes. In the case of KodakRoyal-X Pan sheet film, a density range of only 0.1-0.8 was obtainedwith 10 minutes development at 68F.

EXAMPLE 2 Phenidone 2.0 g Sodium Sulfite 40.0 g Glycin 10.0 g SodiumBisulfite 25.0 g Kodalk 25.0 g Water to 1 liter EXAMPLE 3 Phenidone 2.0g Sodium Sulfite 40.0 g Glycin 10.0 g Sodium Bisulfite 25.0 g Kodalk50.0 g Water to l liter The developer of Example 3, with a 10 minuteprerinse in NaHSO produced with 12 minutes development at 68F, anegative on RXP with a gamma of 0.64 and no loss of toe speed. All stepsof the gray scale were visible upon visual inspection. Further tests ofthis formula resulted in lower gamma (0.55) with all gray scale stepsvisible. The higher gamma in the previous test was probably attributableto the minute pre-rinse. However, it was found that for a givendevelopment time, the NaHSO treatment had no effect on toe speed. It islikely that the increased gamma, if desired, can be attained morequickly by a slight increase in development time.

Tests were also made on Plus-X and 2,475 emulsions, with similarresults. The gamma obtained by 12 minutes development at 68F was 0.5.Prints from both of these films had excellent shadow detail, and fullydetailed highlights. Developing times are about the same as with KodakD-76 but the gammas are of course lower.

Machine processing such as in the 3-90 Filmline spray processer has beenused successfully. Development of XT-Pan is at 85F and 40 ft./min.(slightly less than 2 min. developing time), and the gamma obtainedabout 0.40. To reduce oxidation due to the great developer-air surfacecharacteristic of spray processing, the developing chamber is filledwith gaseous N and a small positive N pressure is maintained duringprocess ing. As much as 2,400 feet of 35 mm XT-Pan films has beenprocessed in one run, using an unmodified developer of Example 3 as areplenisher.

The glycin-phenidone developer of this invention, as illustrated inExamples 2 and 3 produces somewhat higher gammas than the prior artdeveloper of Example 1 and also increases the toe speed of most of thefilms tested, as compared with standard processing with Solumatdeveloper. The dynamic range is increased by at least 10X, andresolution in regions of high and overexposure is improved.

It will be understood that the foregoing description of this inventionis presented for purposes of illustration only, and that the scope ofthe invention is not to be limited in any way except as defined by theappended claims.

What is claimed is:

1. A photographic developer composition comprising an aqueous solutionconsisting essentially of a mixture of 5 parts by weight ofN-(p-hydroxyphenyl glycin), 1 part by weight of l-phenyl-3-pyrazolidone,20 parts by weight of sodium sulphite, 12.5 parts by weight of sodiumbisulfite, 12.5 to 25 parts by weight of a sodium metaborate alkalistabilizer and sufficient water to make one liter of said aqueoussolution.

